Analysis of Direct Current Motors in Dynamic Regimes Using Numerical Techniques


The electromechanical converters and the electric drive systems where they are parts are generally nonlinear systems due to the nonlinear properties of the materials they are built from, as well as the multiple dependencies between their electrical, magnetical and mechanical parameters. However, under certain conditions (e.g. operation on the linear part of the characteristics), some simplifying hypo-theses are accepted, which allow the treatment of systems as linear systems. This simplifies their analysis and solutions could be obtained with acceptable errors. So the electrome-chanical converters and the electric drive systems can be analyzed as linear or nonlinear systems, depending on their properties and on the equations that govern them. Thus, analytical or numerical solving techniques can be used in order to obtain the solution, i.e. the variation in time of some electric, magnetic or mechanic quantities. In this paper a separately excited direct current motor that drives a me-chanical load is analyzed. The transient processes due to startup or sudden change of torque are analyzed both ana-lytically and numerically. Two techniques – namely numeri-cal solving using a Runge-Kutta method and respectively using an equivalent electrical scheme corresponding to the entire driving system – were used. By comparing the ob-tained numerical and analytical results a very good correla-tion between the different solving methods was proved. Thus, this paper offers alternative and viable analysis tech-niques, suitable for the dynamic regimes of the driving sys-tems with direct current motors. images